Meeting Abstract
Temperature has predictable effects on many biological processes, and yet the effects of temperature on parasites are less well understood compared to that of free-living animals. Parasite reproduction could be optimized in a variety of ways, many of which are likely to be affected by temperature – from increased propagule production, to increased propagule longevity or increased development speed. We conducted lab experiments evaluating the effects of temperature on parasite larval production and development in the brooding parasitic castrator Loxothylacus panopaei in its mud crab host Eurypanopeus depressus. Parasitized (with single and double infections) and unparasitized hosts were exposed for 209 days to a range of temperatures (5 to 35°C in increments of 5C) commonly experienced in the field. All parasitic larvae released from crabs were collected, quantified and measured. We found that parasite egg size stayed constant over time, and that temperature had a non-linear effect on parasite egg and nauplii size, with the largest eggs and nauplii around 15-20°C. At 20&decC nauplii also increased in size over the time, and were larger in the hosts with a single infection that a double infection. Development time to the cyprid stage increased with temperature, while cyprid size increased with time, and decreased with brood size. Interestingly, egg and nauplii size were maximized around the same temperature as brood size, but cyprid size was not. As larvae are lecithotrophic, it is possible that increased size confers an increase in longevity and therefore increased transmission potential. With limited resources, larvae at temperatures above optima are developing faster but at the expense of size, number and host survival – which together could decrease transmission potential at higher temperatures.
